Kyushu University Academic Staff Educational and Research Activities Database
List of Presentations
Ozaki Yukiko Last modified date:2022.03.31

Professor / Department of Materials Science and Engineering,Faculty of Engineering / Department of Materials Science and Engineering / Faculty of Engineering


Presentations
1. Takuya Takashita, Yukiko Ozaki, Influence of Iron powder space factor on hysteresis loss of pure iron powder cores., EuroPM2020, 2020.09.
2. Effect of Pore Configurations on Crack Initiation during Tensile Deformation of High-Density Sintered Pure Iron.
3. Effect of preheating under glass transition temperature on green density of ferrous metallic glass powder powders by viscous flow compaction.
4. Yukiko Ozakia, Yasutaka Mugita, Masatoshi Aramaki, Satoshi Ooue, Kosuke Ashizukab, Akihisa Takeuchi, Masayuki Uesugi and Osamu Furukimia, Four-dimensional (4D) Observation of Ductile Fracture in Sintered Iron using Synchrotron X-ray Laminography , EuroPM 2018 Conference and Exhibitions, Birbao, 2018.10, Using synchrotron X-ray laminography, time evolution of the 3-dimensional (3D) morphology of micropores in sintered iron during a tensile test is revealed for the first time. The 3D snapshots showed networked open pores growing wider than 20 m of width along the tensile direction, resulting in the internal necking of the specimen. Finally, the enlarged-open pores initiated cracks perpendicular to tensile direction by coalescing with surrounding micro-voids pre-existent or secondary generated just before fracture. Therefore, by the topological analysis of their barycentric positions, these micro-voids formed 2-demensional networks in the area within about 20 m round. It indicates that coalescence of micro-voids could occur on share planes formed close to the enlarged-open pore by strain accumulation and play an important role in the crack-initiation..
5. Muhammad Kozin, Naoya Yamada, Masatoshi Aramaki, Yukiko Ozaki ,Osamu Furukimi, Wear Resistance of Sintered Pure Iron Treated by Acetylene Gas Carburizing Process, JSPM International Conference on Powder and Powder Metallurgy 2017 ~60th Anniversary, 2017.11, The wear resistance without lubrication of sintered pure iron treated by vacuum carburizing process was investigated. The sliding test results revealed that the wear volume of the specimen treated by the C2H2 gas carburizing decreased about 75% in comparison with the one without the heat treatment. The wear profile observation by Laser microscope of friction surface for the specimen treated by the C2H2 gas carburizing was seemed to be a relatively shallow. In contrast, in specimen without the heat treatment, the relatively deep valley was observed. In addition, a micro-ploughing track and relatively deep scar parallel to the sliding direction which is the characteristic of abrasive wear were observed in the specimen without the heat treatment. Nano-indentation hardness at near the surface of the specimen treated the C2H2 gas carburizing increased from value of HIT amounted to 1751 N/mm2 before heat treatment to 7699 N/mm2 after the heat treatment. The EBSD analysis results showed that the carburized layer consisted of a tempered martensitic phase and a small amount of a retained austenite phase. From these results, it can be concluded that the enhanced wear resistance of the C2H2 gas carburizing specimen is attributed to the increase in the hardness due to the presence of the martensitic phase layer at the surface. This layer is considered to inhibit the surface degradation due to micro-ploughing or exfoliation resulting in a high wear rate..
6. Takashita,Takuya, Nakmaura, Naomichi, Ozaki, Yukiko, Influence of Microstructure on Hysteresis Loss of Pure Iron Powder Core., World PM2016 Congress & Exhib, 2016.10, [URL].
7. Hojo,J., Kiyonaga,T., Hara,H., Kawano,T., Ozaki,Y., Fundamental Research on Sintering Behavior of Iron Powder with Various Additives., Powder Metallurgy World Congress & Exhibition., 2012.06.
8. Maetani,Toshio, Unami,Shigeru, Ozaki,Yukiko, Yamanichi,Y., Properties of sintered compacts and heat-treated compacts after sintering made of low Cr prealloyed steel powder. , Euro PM 2013, 2013.09.
9. Unami,S., Ozaki,Y., Properties of sintered compacts made of Ni-free pre-mixed powder based on low Mo prealloyed steel powder., PM2010 Powder Metall. World Congr., 2010.10.
10. Unami,S., Ozaki,Y., Effect of copper addition on mechanical properties of sintered and case-hardened compacts made of low molybdenum prealloyed steel powder., Powder Metallurgy World Congress & Exhibition., 2012.10.
11. Maetani,Toshio, Unimi,Shigeru, Ozaki, Yukiko, Effect of a Newly Developed Machinability Aid on Machinability of Sintered Steels., Powder Metallurgy World Congress & Exhibition., 2012.10.
12. Shimotomai,M., Fukuda,Y., Fujita,A., Ozaki,Y., Corrosion-Resistant Nd-TM-B Magnet., INTERMAG '90, 1990.09.
13. Mochizuki,T., Iida,K., Fujima,T., Shiraki,N., Takagi,K., Unami,S., Ozaki,Y., Compressibility and Sinterability Improvement of Cr Prealloyed Steel Powders by Controlling Particle Size Distribution., Powder Metallurgy World Congress & Exhibition., 2012.10.
14. Fukuda,Y., Fujita,A., Kitano,Y., Ozaki,Y., Shimotomai,M., Coercivity and toughness of TiB2 dispersed Nd-(Fe,Co,Ni)-B sintered magnets., 12th Int. Workshop on Rare Earth Magnets and Their Applications, 1992.10.
15. Takajyo,S., Ozaki,Y., Frequency dependence of the permeability and iron loss of iron powder dust cores for high frequency applications. Power Convers., Motion HFPC Conf. 1998, 1998.09.